The present invention relates in general to universal joins of the Cardan type and in particular to a new and useful universal joint comprising a first and second joint yoke with throughbores arranged at the ends of the yoke arms of the joint yokes, whose axes lie in a common plane, a trunnion cross comprising four trunnions arranged in a common plane at right angles with respect to each other, and bearing cups placed upon the trunnions with interposition of bearing members, whereby, respectively, two trunnions lying in the same axis together with the bearing cups are received and secured in the two bores of the first joint yoke and to the other trunnions together with the bearing cups are received and secured in the two bores of the second joint yoke.
In such universal joints of the Cardan type, there exists the problem that because of the construction of the yoke arms, there are unequal cross-sectional conditions along the bore and with this, unequal strength and strain conditions in the radial cross-sectional planes of the bore which receives the bearing cups. This results in an unsymmetrical and, thus, unfavorable load distribution, particularly upon the bearing components of the universal joint. The force transmittal occurs preponderantly through the bearing sector which is to be assigned to the stiffer portion of the yoke arm. The other portion of the joint support responsible for the circumferential force transmittal carries a lesser proportion of the load because of the increased elasticity of the end of the yoke arm and, thus, is not completely utilized as far as its capacity of transmittal is concerned. From this, there follows a partial overload of the joint cross support in the stiffer portion of the yoke arms of the joint yoke. This causes a definite reduction in the useful life of the joint because of premature material fatigue.
Thus, the principal direction of force transmittal deviates from the direction of torque transmittal, wherein, in addition, there arises a force component in the direction of the axis which leads to a migration of the two trunnion arms away from each other because said force component acts eccentrically ofthe axis of rotation of the respective joint yoke.